A) Field of the Invention
This invention relates to a liquid crystal display device, and more specifically to a liquid crystal display device suitable for usage at a low temperature.
B) Description of the Related Art
A response speed of a LCD becomes quite slow at a low temperature because viscosity of liquid crystals becomes higher. If the response speed is slow, blurring or ghost images may appear in a motion picture so that a display quality will be significantly lowered. Improvement of the response speed at a low temperature has been desired for a liquid crystal display used for a car-mounted device, an outdoor display board, a mobile phone, a mobile television set, etc. JPA 2000-93841 teaches a liquid crystal display device wherein a whole liquid crystal cell is heated by a plane heating source by equipping a panel heater on a glass substrate. Thermal efficiency is considered to be low because a liquid crystal layer is heated via the glass substrate and a polarizing filter. Therefore, it is difficult to utilize in a mobile phone, which has a limited power source.
JPA 2005-24866 teaches a crystal liquid display device wherein a liquid crystal layer is heated by irradiating emitted light of an infrared rays (IR) light emitting diode (LED) to a whole liquid crystal cell via a light guide. It is considered that irradiated infrared rays are mainly absorbed by a polarizing filter. Absorption of the infrared rays by the liquid crystal layer depends on an infrared ray absorption property of liquid crystal material. Thermal efficiency is considered to be low.